Composite Susceptor Particles for Curie-Temperature Heat Control

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Solution Overview

Problem

Existing susceptor assemblies for inductively heating aerosol-forming substrates face limitations in heating efficiency and temperature control, necessitating active power regulation to prevent overheating.

Innovation Solution

A composite susceptor particle design comprising a ferromagnetic or ferrimagnetic core with high magnetic permeability and an electrically conductive shell, which self-regulates heat generation by changing magnetic properties at the Curie temperature, enhancing heating efficiency and temperature control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a single susceptor material is used for heating, then the structure is simple, but heating efficiency is insufficient and temperature control is poor

Engineering Contradiction:
Improvestructure simplicityVSAvoidheating efficiency
Core Design Contradiction:
Ease of manufactureVSUse of energy by moving object

Solution Approach 1:

The patent applies composite materials by combining ferromagnetic susceptor particles (for heating efficiency) with paramagnetic temperature marker particles (for temperature control) within a single susceptor assembly. This composite structure resolves the contradiction by achieving both high heating efficiency and improved temperature control without requiring complex multi-component systems

Inventive Principle:
Principle #40Composite materials

2Measurement precision

If multiple susceptor materials are used for temperature control, then temperature monitoring capability is improved, but the system complexity increases

Engineering Contradiction:
Improvetemperature control capabilityVSAvoidsusceptor structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent merges the heating function and temperature monitoring function into a single integrated susceptor assembly by combining ferromagnetic particles and paramagnetic particles in one structure. This resolves the contradiction by achieving temperature control capability without increasing device complexity, as both functions are unified in one composite susceptor system

Inventive Principle:
Principle #5Merging (Combining)

3Temperature

If active power regulation is implemented to prevent overheating, then temperature control is achieved, but the system complexity and energy loss increase

Engineering Contradiction:
Improvetemperature controlVSAvoidactive regulation system complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

The patent implements self-service by using the intrinsic Curie temperature transition of paramagnetic particles to automatically indicate when the susceptor reaches its maximum operating temperature. This eliminates the need for active power regulation systems, resolving the contradiction by achieving temperature control without additional system complexity or energy loss from active regulation

Inventive Principle:
Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The composite susceptor particles provide improved heating efficiency and temperature control, reducing the need for active temperature regulation by automatically adjusting heat generation at the Curie temperature, preventing overheating.

Implementation Method 1

the substrate may be arranged in thermal proximity or direct physical contact with a susceptor which is capable to generate heat due to at least one of eddy currents or hysteresis losses when it is exposed to an alternating magnetic field

Methodology Applied
Scientific EffectHysteresis losses: Hysteresis

Implementation Method 2

the substrate may be arranged in thermal proximity or direct physical contact with a susceptor which is capable to generate heat due to at least one of eddy currents or hysteresis losses when it is exposed to an alternating magnetic field

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 3

the second susceptor material is chosen such as to have a Curie temperature corresponding to a predefined operating temperature of the susceptor assembly. At its Curie temperature, the magnetic properties of the second susceptor change from ferromagnetic or ferrimagnetic to paramagnetic

Methodology Applied
Scientific EffectCurie temperature transition: Curie Point (ferromagnetic)

Data Source

PatentEP4162769B1Susceptor assembly comprising one or more composite susceptor particles
Publication Date: 2025.10.22 PHILIP MORRIS PRODUCTS SA
  • EP4162769B1 patent drawingFigure 1~4
  • EP4162769B1 patent drawingFigure 2

AI summary

The present disclosure relates to a susceptor assembly comprising one or more composite susceptor particles for inductively heating an aerosol-forming substrate under the influence of an alternating magnetic field. Each one of the one or more susceptor particles comprises a particle core and a particle shell entirely encapsulating the particle core. The particle core comprises or is made of a ferromagnetic or ferrimagnetic core material having a relative magnetic permeability of at least 200 for frequencies up to 10 kHz at a temperature of 20 degree Celsius. The particle shell comprises or is made of an electrically conductive shell material. The disclosure further relates to an aerosol-generating article comprising such a susceptor assembly as well as to an aerosol-generating system comprising such an article and an aerosol-generating device. In addition, the disclosure relates to a method of manufacturing such a susceptor assembly.